In a patient with a normal platelet count of 240 ×10⁹/L, microcytic iron‑deficiency anemia and acute kidney injury likely secondary to sepsis, what is the most likely diagnosis and how should it be managed?

Clinical Assessment: Sepsis with Normal Platelet Count

In a patient with sepsis, acute kidney injury, and a normal platelet count of 240 ×10⁹/L, the primary diagnosis is sepsis-induced organ dysfunction without coagulopathy, and management should focus on aggressive sepsis resuscitation, source control, and prophylactic anticoagulation with unfractionated heparin given the renal impairment.

Initial Diagnostic Approach

Rule Out Thrombotic Microangiopathy (TMA)

• A normal platelet count of 240 ×10⁹/L effectively excludes most thrombotic microangiopathies as the primary diagnosis, since TMA characteristically presents with thrombocytopenia (platelet count <150 ×10⁹/L) 1, 2, 3
• However, recognize that athrombocytopenic TMA exists in approximately 44% of biopsy-proven cases, though this is rare and typically still shows elevated LDH 4
• If clinical suspicion for TMA persists despite normal platelets, check LDH, peripheral smear for schistocytes, and serum creatinine—if creatinine >1.8 mg/dL and platelets >30 ×10⁹/L, severe ADAMTS13 deficiency is highly unlikely (negative predictive value 92-98%) 5

Assess for Septic Coagulopathy

• Monitor PT ratio (not INR), D-dimer, platelet count, and fibrinogen to determine prognosis and guide escalation of care 6
• Worsening of these parameters indicates need for more aggressive critical care support 6
• PT ratio should be kept <1.5 if coagulopathy develops 6, 7, 8
• Fibrinogen should be maintained >1.5 g/L if coagulopathy is present 6, 7

Management Strategy

Prophylactic Anticoagulation

All hospitalized patients with sepsis should receive prophylactic anticoagulation unless contraindicated 6, 8

Contraindications to prophylactic heparin:

• Active bleeding 6, 8
• Platelet count <25 ×10⁹/L 6, 8
• Note: Abnormal PT or aPTT is NOT a contraindication 8

Choice of anticoagulant in ESRD/AKI:

• Use unfractionated heparin (UFH) rather than low molecular weight heparin (LMWH) in this patient with acute kidney injury 8
• UFH does not require dose adjustment in renal failure and is the preferred agent in ESRD 8
• LMWH requires monitoring in severe renal impairment 6, 8
• Prophylactic anticoagulation reduces mortality in septic patients, particularly those with sepsis-induced coagulopathy score ≥4 6

Blood Product Thresholds in Sepsis

With a platelet count of 240 ×10⁹/L, no platelet transfusion is indicated 6

Standard sepsis transfusion thresholds:

• Prophylactic platelet transfusion only when <10 ×10⁹/L without bleeding, or <20 ×10⁹/L with significant bleeding risk 6
• Higher platelet counts ≥50 ×10⁹/L required for active bleeding, surgery, or invasive procedures 6, 7
• RBC transfusion only when hemoglobin <7.0 g/dL, targeting 7.0-9.0 g/dL 6
• Fresh frozen plasma should not be used to correct laboratory clotting abnormalities in the absence of bleeding or planned invasive procedures 6

Iron Deficiency Anemia Management

• Defer intravenous iron replacement until sepsis resolves and patient is hemodynamically stable 9
• The microcytic iron-deficiency anemia is a chronic issue that does not require urgent correction during acute sepsis
• Once stable, iron sucrose can be administered in hemodialysis patients at 100 mg per dialysis session for 10 consecutive sessions 9

Monitoring Strategy

Serial Laboratory Assessment

• Daily monitoring of platelet count, PT ratio, D-dimer, and fibrinogen to track for development of septic coagulopathy 6
• Ensure platelet count remains >25 ×10⁹/L while on prophylactic anticoagulation (>50 ×10⁹/L if any bleeding develops) 7, 8
• Rising D-dimer (3-4 fold increase) or worsening PT ratio signals need for escalation of care 6

Critical Pitfalls to Avoid

• Do not withhold prophylactic anticoagulation based solely on elevated PT/aPTT—these are not contraindications in septic coagulopathy 8
• Do not use LMWH in patients with acute kidney injury or ESRD without anti-Xa monitoring—use UFH instead 8
• Do not transfuse platelets prophylactically at this normal platelet count 6
• Do not use PT ratio and INR interchangeably—guidelines specifically reference PT ratio <1.5, not INR 6, 7, 8